I have found a bug in your code

[usasaradhi]

You have taken x range between 1, 4. and y range between -1, 1. In every iteration best location should return X with in range 1, 4 and Y in -1, 1. But your code returning X negative values.
I have solved this by putting velocities of particle to 0.0 in initialisation.
Please check it update me if i am wrong.

public void initializeSwarm() {
		Particle p;
		for(int i=0; i<SWARM_SIZE; i++) {
			p = new Particle();
			
			// randomize location inside a space defined in Problem Set
			double[] loc = new double[PROBLEM_DIMENSION];
			loc[0] = ProblemSet.LOC_X_LOW + generator.nextDouble() * (ProblemSet.LOC_X_HIGH - ProblemSet.LOC_X_LOW);
			loc[1] = ProblemSet.LOC_Y_LOW + generator.nextDouble() * (ProblemSet.LOC_Y_HIGH - ProblemSet.LOC_Y_LOW);
			
                        System.out.println("X value is " + loc[0]);
                        System.out.println("Y value is " + loc[1]);
                        Location location = new Location(loc);
			
			// randomize velocity in the range defined in Problem Set
			double[] vel = new double[PROBLEM_DIMENSION];
			//vel[0] = ProblemSet.VEL_LOW + generator.nextDouble() * (ProblemSet.VEL_HIGH - ProblemSet.VEL_LOW);
			//vel[1] = ProblemSet.VEL_LOW + generator.nextDouble() * (ProblemSet.VEL_HIGH - ProblemSet.VEL_LOW);
			vel[0] = 0.0;
                        vel[1] = 0.0;
                        Velocity velocity = new Velocity(vel);
			
			p.setLocation(location);
			p.setVelocity(velocity);
			swarm.add(p);
		}
	}